[albertjan]

(Contributor to skulpt and pypy.js here)

That is a difficult question to ask and I think the original developer of pypy.js Ryan Kelly is most suited to answer it. There are some people that have tried feeding the asm.js from pypy.js to the asm.js -> wasm compiler.

Which with a lot of fiddling may work for the non-jitted version. But if you want all the pypy speed you'll want to jit wasm to the browser.

I would love to know if you can do synchronous calls in wasm.

[meredydd]

As Albert-Jan and I discussed at PyCon this weekend, the long-term future for Skulpt quite possibly involves compiling to WASM rather than Javascript. This is very unlikely to happen until every modern browser supports WASM. Neither Trinket's educational mission nor Anvil's "web apps for the world" mission are compatible with leaving users behind just because their workplace or school runs IE.

The runtime can be remarkably small (Skulpt is 228kb minified and gzipped, including the standard library), so I think it's a feasible target. (Pypy.js is, of course, enormous!)

[steveklabnik]

> This is very unlikely to happen until every modern browser supports WASM

WASM ships in every evergreen browser today: http://caniuse.com/#feat=wasm

Only significant browser missing it is IE; only Edge has support.

[albertjan]

What @meredydd means is, leaving the compiler written in javascript but emitting wasm, so compiling python into wasm with javascript. Too many compilers! :P